A mobile ball cage universal joint

Abstract

The present invention relates to a movable ball cage universal joint, comprising an outer star wheel, a ball cage and an inner star wheel. In an intermediate state, the distance between the inner star wheel and the rear end bottom surface of the inner cavity of the outer star wheel is M, and the wheel circumference of the inner star wheel is in an arc shape with a radius r in the axial direction; the inner cavity of the ball cage comprises a front hole section, a middle hole section and a rear hole section, the radius of the middle hole section is R, the hole wall of the front hole section is in an arc shape with a radius R on a cross section passing through the central axis of the ball cage, and the radius of its front port is h, R>h, the distance between the rear end of the front hole section and the axial center plane of the ball cage is a, the hole wall of the rear hole section is in an arc shape with a radius R on a cross section passing through the central axis of the ball cage, and the radius of its rear port is H, R>H, the front end inner wall is tangent to the inner wall of the middle hole section, and the distance between the front end of the rear hole section and the axial center plane of the ball cage is b; when the inner star wheel moves back and forth in the inner cavity of the ball cage, it contacts and limits the front port and the rear port, S1=2*[a+(R 2 ‑h 2 ) 1 / 2 ‑(r 2 ‑h 2 ) 1 / 2 ],S2=2*[b+(R 2 ‑H 2 ) 1 / 2 ‑(r 2 ‑H 2 ) 1 / 2 ]>M,R>r>h,r>H。

Description

Technical Field

[0001] The present invention relates to the technical field of universal joints, in particular to a movable ball cage universal joint. Background Art

[0002] A universal joint is a component that realizes variable-angle power transmission. It is used in positions where the direction of the transmission axis needs to be changed. It is the "joint" component of the universal joint device of the automobile drive system.

[0003] Ball joint universal joint is widely used in various industries, mainly including outer star wheel 1, ball joint 2 and inner star wheel 3. Figure 1 As shown, cage 2 is mounted within the outer planetary wheel cavity 11 in the center of outer planetary wheel 1, while inner planetary wheel 3 is mounted within cage cavity 23 within cage 2 and is capable of axially moving forward and backward therein. A plane perpendicular to the center axis of inner planetary wheel 3 and passing through the midpoint of the ball path on inner planetary wheel 3 is called inner planetary wheel axial center plane 31, while a plane perpendicular to the axis of cage 2 and passing through the center of cage window 21 (for mounting the balls) is called cage axial center plane 22. In existing cage 2 universal joints, cage cavity 23 is a circular hole with a gradually varying diameter along the axial direction. Its inner wall surface is arc-shaped along the axial direction. Cage cavity 23 is symmetrical about cage axial center plane 22, with a larger inner diameter in the middle and smaller inner diameters at the front and rear. The circumference of inner planetary wheel 3 also varies in diameter axially and is symmetrical about inner planetary wheel axial center plane 31, with a larger radius in the middle and smaller radius at the front and rear. The inner star wheel 3 can move forward and backward in the axial direction in the cage cavity 23, and the cage cavity 23 limits the inner star wheel 3 through the front and rear inner walls. Figure 1 The axial center plane 22 of the ball cage is located on the middle positioning surface 12 of the outer star wheel inner cavity 11, and the axial center plane 31 of the inner star wheel is located on the axial center plane 22 of the ball cage. At this time, the ball cage 2 and the inner star wheel 3 can move in the front-rear direction. Figure 2 and attached Figure 3 As shown in the figure, the circumference of the inner star wheel 3 contacts the inner wall of the cage cavity 23 to limit the inner star wheel 3 from escaping from the cage cavity 23.

[0004] In existing ball cage universal joints, the ball cage 2 has equal tensile and compression limit distances for the inner star wheel 3. In this application, the tensile limit distance refers to the distance the inner star wheel 3 moves relative to its intermediate state when stretched to abut the front end of the ball cage inner cavity 23, and the compression limit distance refers to the distance the inner star wheel 3 moves relative to its intermediate state when compressed to abut the rear end of the ball cage inner cavity 23 (not considering whether the inner star wheel 3 will contact the outer star wheel inner cavity 11). During assembly of the universal joint assembly, the inner star wheel 3 is directly pressed to the bottom of the outer star wheel inner cavity 11 via the real shaft. With this existing design, the circumferential surface of the inner star wheel 3 is prone to contact with the rear end of the ball cage inner cavity 23. See attached. Figure 3 The transmission path of the pressing force is: real shaft-inner star wheel 3-ball cage 2-steel ball-outer star wheel 1 (ballway). When the pressing force is too large, the ball cage 2 will be damaged. Summary of the Invention

[0005] In view of the shortcomings of the prior art mentioned above, the technical problem to be solved by the present invention is to provide a mobile ball cage universal joint, which can limit the inner star wheel and ensure that the inner star wheel will contact the bottom of the inner cavity of the outer star wheel while not contacting the inner cavity wall of the ball cage in the compressed state, thereby avoiding crushing the ball cage.

[0006] To achieve the above-mentioned purpose, the present invention provides a movable ball cage universal joint, comprising an outer star wheel, a ball cage and an inner star wheel, wherein the ball cage is installed in the inner cavity of the outer star wheel of the outer star wheel, a ball cage inner cavity is provided in the ball cage, and the inner star wheel is installed in the inner cavity of the ball cage, and in the intermediate state, the distance between the rear end bottom surfaces of the inner star wheel and the inner cavity of the outer star wheel is M, the wheel circumference of the inner star wheel is an arc shape with a radius of r on the cross section passing through the central axis, and the wheel circumference is symmetrical front and back about the axial center plane of the inner star wheel of the inner star wheel; the inner cavity of the ball cage comprises a front hole section, a middle hole section and a rear hole section from front to back, the middle hole section is a straight hole of equal diameter with a radius R, the inner diameter of the front hole section gradually increases from front to back, and the hole wall of the front hole section is along the axis. The cross section through the central axis of the ball cage is in the shape of an arc and has a radius of R. The front port radius of the front hole segment is h, the rear end inner wall is tangent to the inner wall of the middle hole segment, and the distance between the rear end of the front hole segment and the axial center plane of the ball cage is a. The inner diameter of the rear hole segment gradually decreases from front to back. The hole wall of the rear hole segment is in the shape of an arc and has a radius of R on the cross section through the central axis of the ball cage. The rear port radius of the rear hole segment is H, the front end inner wall is tangent to the inner wall of the middle hole segment, and the distance between the front end of the rear hole segment and the axial center plane of the ball cage is b. When the inner star wheel moves forward in the inner cavity of the ball cage, it contacts the edge of the front port of the front hole segment, and when it moves backward, it contacts the edge of the rear port of the rear hole segment. Wherein, S1=2*[a+(R 2 -h 2 ) 1 / 2 -(r 2 -h 2 ) 1 / 2] , S2=2*[b+(R 2 -H 2 ) 1 / 2 -(r 2 -H 2 ) 1 / 2 ]>M, R>r>h, r>H, S1 and S2 are the tensile limit distance and compression limit distance of the ball cage to the inner star wheel respectively.

[0007] Furthermore, the ball cage is also provided with a front straight hole connected to the front end of the ball cage inner cavity, and a rear straight hole connected to the rear end of the ball cage inner cavity. The radius of the front straight hole is h, and the radius of the rear straight hole is H.

[0008] As described above, the mobile ball cage universal joint of the present invention has the following beneficial effects:

[0009] By dividing the inner cavity of the cage into a front hole section, a middle hole section and a rear hole section, and setting the circumferential surface of the inner star wheel to be a spherical surface that is symmetrical front and back, and setting corresponding dimensions to meet the requirements, the cage can limit the inner star wheel. At the same time, in the compressed state, it can ensure that the inner star wheel will contact the bottom of the inner cavity of the outer star wheel while not contacting the inner cavity wall of the cage, thereby avoiding the force on the cage when the inner star wheel is compressed to the extreme position. In this way, when the outer spline of the intermediate shaft is pressed into the inner spline of the inner star wheel during assembly, the pressing force generated will not be transmitted to the cage, so even if a large pressing force is generated, the cage will not be damaged. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a structural diagram of an existing mobile ball cage universal joint.

[0011] Figure 2 The figure is a structural diagram of an existing mobile ball cage universal joint in a stretched state.

[0012] Figure 3 This is a schematic diagram of the structure of an existing mobile ball joint in a compressed state.

[0013] Figure 4 The figure is a schematic structural diagram of the ball cage in the movable ball cage universal joint of the present invention.

[0014] Figure 5 It is a schematic structural diagram of the inner star wheel in the movable ball cage universal joint of the present invention.

[0015] Figure 6 It is a structural schematic diagram of the movable ball cage universal joint of the present invention in the middle state.

[0016] Figure 7 This is a schematic structural diagram of the movable ball cage universal joint of the present invention in a stretched state.

[0017] Figure 8This is a schematic structural diagram of the movable ball cage universal joint of the present invention in a compressed state.

[0018] Figure 9 This is a schematic diagram of the movable ball cage universal joint of the present invention during assembly and press-fitting.

[0019] Description of Figure Numbers:

[0020] 1-outer planet wheel, 11-inner cavity of outer planet wheel, 12-middle positioning surface; 2-cage, 21-cage window, 22-axial center plane of the cage, 23-inner cavity of the cage, 231-front hole section, 232-middle hole section, 233-rear hole section, 24-front straight hole, 25-rear straight hole; 3-inner planet wheel, 31-axial center plane of the inner planet wheel; 4-tensile contact point; 5-compression contact point; 6-real axis. DETAILED DESCRIPTION

[0021] The following describes the implementation of the present invention through specific embodiments. People skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification.

[0022] It should be noted that the structures, proportions, sizes, etc. depicted in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the conditions for the implementation of the present invention. Therefore, they have no substantial technical significance. Any modification of the structure, change in the proportional relationship, or adjustment of the size should still fall within the scope of the technical content disclosed by the present invention without affecting the efficacy and purpose of the present invention. At the same time, the terms such as "upper", "lower", "left", "right", "middle", etc. quoted in this specification are only for the convenience of description and are not used to limit the scope of the implementation of the present invention. Changes or adjustments in their relative relationships should also be regarded as the scope of the implementation of the present invention without substantially changing the technical content.

[0023] See also Figures 4 to 9 The present invention provides a mobile ball cage universal joint, including an outer star wheel 1, a ball cage 2 and an inner star wheel 3. The ball cage 2 is installed in the outer star wheel inner cavity 11 in the outer star wheel 1. The ball cage 2 is provided with a ball cage inner cavity 23. The inner star wheel 3 is installed in the ball cage inner cavity 23 and can move in the ball cage inner cavity 23. The outer star wheel 1, the ball cage 2 and the inner star wheel 3 are coaxial, with the axial direction as the front-to-back direction. In the intermediate state, the distance between the inner star wheel 3 and the rear end bottom surface of the outer star wheel inner cavity 11 is M.

[0024] In the present invention, the circumference of the inner star wheel 3 is an arc-shaped with a radius of r on the cross section passing through the central axis, that is, the circumference of the inner star wheel 3 extends along the arc in the axial direction, the circumference of the inner star wheel 3 is a partial spherical surface, and the circumference is symmetrical front to back about the axial center plane 31 of the inner star wheel; the inner cavity 23 of the ball cage includes a front hole section 231, a middle hole section 232 and a rear hole section 233 from front to back, the middle hole section 232 is a straight hole of equal diameter with a radius R, the inner diameter of the front hole section 231 gradually increases from front to back, the hole wall of the front hole section 231 is an arc-shaped with a radius R on the cross section passing through the central axis of the ball cage 2, the front port radius of the front hole section 231 is h, and the rear end inner wall is tangent to the inner wall of the middle hole section 232, that is, the rear port radius of the front hole section 231 is R, in other words, the inner wall surface of the front hole section 231 is a spherical surface with a radius R, and the front hole section 231 The distance between the rear end and the axial center plane 22 of the ball cage 2 is a, that is, the length of the middle hole section 232 in front of the axial center plane 22 of the ball cage is a, the inner diameter of the rear hole section 233 gradually decreases from front to back, the hole wall of the rear hole section 233 is an arc with a radius R on the cross section passing through the central axis of the ball cage 2, the rear port radius of the rear hole section 233 is H, the front end inner wall is tangent to the inner wall of the middle hole section 232, that is, the rear port radius of the rear hole section 233 is H, and the distance between the front end of the rear hole section 233 and the axial center plane 22 of the ball cage is b, that is, the length of the middle hole section 232 behind the axial center plane 22 of the ball cage is a; when the inner star wheel 3 moves forward in the ball cage inner cavity 23, it can contact the front port edge of the front hole section 231, and when it moves backward, it can contact the rear port edge of the rear hole section 233, where S1=2*[a+(R 2 -h 2 ) 1 / 2 -(r 2 -h 2 ) 1 / 2 ] , S2=2*[b+(R 2 -H 2 ) 1 / 2 -(r 2 -H 2 ) 1 / 2 ] >M, R>r>h, r>H, S1 and S2 are the stretching limit distance and compression limit distance of the ball cage 2 to the inner star wheel 3 respectively.

[0025] The basic working principle of the mobile ball cage universal joint of the present invention is as follows: when designing a product, the parameters S1, S2, R, r and M are determined by relevant design factors and are known parameters. In the present invention, reasonable values are set by adjusting the parameters H, h, a and b to meet the following conditions: S1=2*[a+(R 2 -h 2 ) 1 / 2 -(r 2 -h 2 ) 1 / 2] , S2=2*[b+(R 2 -H 2 ) 1 / 2 -(r 2 -H 2 ) 1 / 2 ]>M, R>r>h, r>H, to ensure that the cage 2 can limit the inner star wheel 3, and in the compressed state, the inner star wheel 3 can contact the bottom of the outer star wheel inner cavity 11 while not contacting the cage inner cavity 23, avoiding crushing the cage 2. The specific principle is as follows:

[0026] See also Figure 7 Since r>h, the inner star wheel 3 will not escape from the front end of the cage cavity 23. In this application, during the stretching process of the movable cage universal joint, the forward displacement of the inner star wheel 3 is equal to twice the forward displacement of the cage 2. In the stretched state, the circumferential surface of the inner star wheel 3 needs to be in contact with the front end of the front hole section 231 to form a stretching contact point 4. In this way, k1=(R 2 -h 2 ) 1 / 2 -(r 2 -h 2 ) 1 / 2 , a+ k1 is the displacement of the inner star wheel 3 relative to the cage 2, then the stretching limit distance of the cage 2 to the inner star wheel 3 is S1=2*(a+ k1)=2*[a+(R 2 -h 2 ) 1 / 2 -(r 2 -h 2 ) 1 / 2 ], since the stretching distance of the inner star wheel 3 is specified when the mobile ball cage universal joint is designed, that is, the stretching limit distance S1 of the ball cage 2 to the inner star wheel 3 is determined, therefore, by setting appropriate values of h and a to meet the above-mentioned dimensional requirements, it can be achieved that the circumferential surface of the inner star wheel 3 contacts and limits the front end of the front hole section 231 when in the specified extended state.

[0027] See also Figure 8 Since r>H, the inner star wheel 3 will not escape from the rear port of the cage cavity 23. During the compression process, the compression limit distance S2 of the cage 2 on the inner star wheel 3 is the distance moved when the inner star wheel 3 contacts the cage 2. This distance does not take into account the contact between the inner star wheel 3 and the bottom of the outer star wheel cavity 11. Figure 8 Assuming that the circumference of the inner star wheel 3 is in contact with the rear end of the rear hole section 233 in the compression state, and the contact constitutes the compression limit point, it is required that k2=(R 2 -H 2 ) 1 / 2 -(r 2 -H 2 ) 1 / 2, b + k2 is the displacement of the inner star wheel 3 relative to the ball cage 2. During the compression process of the mobile ball cage universal joint, the backward displacement of the inner star wheel 3 is equal to twice the backward displacement of the ball cage 2. Therefore, S2=2*(b+ k2)=2*[b+(R 2 -H 2 ) 1 / 2 -(r 2 -H 2 ) 1 / 2 ], when S2>M, the inner star wheel 3 contacts the bottom of the outer star wheel cavity 1111 before reaching the compression limit distance S2 during the compression movement. At this time, the circumferential surface of the inner star wheel 3 does not contact the rear end of the rear hole section 233. Therefore, by setting appropriate values of H and b to meet the above-mentioned dimensional requirements, it can be achieved that during compression, the inner star wheel 3 contacts the bottom of the outer star wheel cavity 11 while not contacting the inner wall of the cage cavity 23.

[0028] When assembling the universal joint assembly, refer to Figure 9 The real shaft 6 presses the inner star wheel 3 directly to the bottom of the outer star wheel inner cavity 11. At this time, the transmission path of the pressing force is: real shaft 6-inner star wheel 3-outer star wheel 1. The ball cage 2 and the steel ball are not subjected to force, avoiding the possibility of the ball cage 2 being damaged by pressure.

[0029] As a preferred design, see Figure 4 The ball cage 2 is further provided with a front straight hole 24 connected to the front end of the ball cage inner cavity 23, and a rear straight hole 25 connected to the rear end of the ball cage inner cavity 23. The radius of the front straight hole 24 is h, and the radius of the rear straight hole 25 is H. By providing the front straight hole 24, the wall thickness at the front end of the front hole section 231 of the ball cage inner cavity 23 can be increased. By providing the front straight hole 24, the wall thickness at the rear end of the rear hole section 233 of the ball cage inner cavity 23 can be increased, so that it can withstand greater pressure when in contact with the inner star wheel 3, thereby ensuring structural stability.

[0030] In summary, the present invention effectively overcomes various shortcomings in the prior art and has high industrial utilization value.

[0031] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A mobile ball cage universal joint, comprising an outer star wheel (1), a ball cage (2) and an inner star wheel (3), wherein the ball cage (2) is mounted in an outer star wheel inner cavity (11) of the outer star wheel (1), a ball cage inner cavity (23) is provided in the ball cage (2), and the inner star wheel (3) is mounted in the ball cage inner cavity (23), and in an intermediate state, a distance M between the rear end bottom surfaces of the inner star wheel (3) and the inner cavity of the outer star wheel (1), characterized in that: The wheel circumference of the inner star wheel (3) is arc-shaped and has a radius of r on a cross section passing through the central axis, and the wheel circumference is symmetrical front to back about the inner star wheel axial center plane (31) of the inner star wheel (3); the ball cage inner cavity (23) includes a front hole section (231), a middle hole section (232) and a rear hole section (233) from front to back, the middle hole section (232) is a straight hole of equal diameter and has a radius of R, the inner diameter of the front hole section (231) gradually increases from front to back, the hole wall of the front hole section (231) is arc-shaped and has a radius of R on a cross section passing through the central axis of the ball cage (2), the front port radius of the front hole section (231) is h, the rear end inner wall is tangent to the inner wall of the middle hole section (232), and The distance between the rear end of the front hole section (231) and the axial center plane (22) of the ball cage (2) is a, the inner diameter of the rear hole section (233) gradually decreases from front to back, the hole wall of the rear hole section (233) is an arc shape with a radius R on the cross section passing through the central axis of the ball cage (2), the rear port radius of the rear hole section (233) is H, the front end inner wall is tangent to the inner wall of the middle hole section (232), and the distance between the front end of the rear hole section (233) and the axial center plane (22) of the ball cage is b; the inner star wheel (3) contacts the front port edge of the front hole section (231) when moving forward in the ball cage inner cavity (23), and contacts the rear port edge of the rear hole section (233) when moving backward, wherein S1=2*[a+(R 2 -h 2 ) 1 / 2 -(r 2 -h 2 ) 1 / 2 ] , S2=2*[b+(R 2 -H 2 ) 1 / 2 -(r 2 -H 2 ) 1 / 2 ] >M, R>r>h, r>H, S1 and S2 are respectively the stretching limit distance and the compression limit distance of the ball cage (2) to the inner star wheel (3); the ball cage (2) is further provided with a front straight hole (24) connected to the front end of the ball cage inner cavity (23), and a rear straight hole (25) connected to the rear end of the ball cage inner cavity (23).

2. The mobile ball joint according to claim 1, characterized in that: The radius of the front straight hole (24) is h, and the radius of the rear straight hole (25) is H.

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